Writing a Novel: Outline Versus Vamp

I'm about done with chapter 3 of my novel and so I've been thinking about method lately. Here's what I've done so far: in the very beginning I did a very, very general outline, basically a one-sentence or short paragraph summary of what happens in each chapter. Then I've been taking it chapter by chapter, including the parts I've outlined for each one and sort of vamping the rest. The thing is, though the vamping is fun, I'm finding that I wish I'd done a more extensive outline.

I know some writers do pages and pages of outlining, and others just have a first sentence and go from their, letting the story go as it may. What do you do? More specifically, what is it like, following your own method? If you vamp the whole time, how do you know its working, where do you come up with ideas for the next scene, etc? If you do extensive outlining, what format do you do it in, how specific do you get?

Any advice, input you have about your own novel-developmental ideas, would be great. What works for you? I'd love some specific ideas.

Thanks and happy writing!
Sarah Allen